Congestion is a major problem in the traffic industry. Traffic congestion is a concern with regard to safety on the roads as well as conservation of energy. County Road Commissions and Departments of Transportation (hereinafter “DOTs”) need to be able to identify and relieve traffic congestion. DOTs use programmable traffic signals as a method to relieve traffic congestion. The ability of DOTs to make good use of the programmable traffic signals is limited by the difficulty in obtaining valid traffic flow and congestion information.
Currently, traffic engineers use derivative information to infer the real measure of performance, e.g., vehicle travel times. Vehicle travel time is the time it takes a vehicle to travel between two or more specified points; such as two intersections or a segment of roadway. Derivative information is information; such as traffic densities and flow speeds at points within the roadway network. Derivative information is obtained through the use of physical induction loops imbedded in the roadway, cameras mounted above the roadway, and temporary air-lines run across the roadway. However, presently there is no way to accurately measure the travel time of a vehicle without intruding into or specifically tracking a vehicle.
Alternate approaches of obtaining travel time information include harvesting information about cell phone mobility from the associations between cell phones and cellular towers, as well as from GPS probes to active phones. For example, as a mobile phone talks on a controlled telecom channel, the mobile phone registers with a basestation or cellular tower. A server in the operation center of the wireless service provider tracks the Electric Serial Number (“ESN”) of the cell phone within a vehicle. The server then calculates the travel time of the vehicle as it moves between towers. Since the ESN is tied to the account of a subscriber, this method creates a history of where the individual subscriber has been. Therefore, this method requires both the co-operation of the cellular carriers and the trust of the subscribers that privacy will not be violated. Additionally, since the cellular towers are not necessarily located near roadways, and cell sizes may be physically quite large, there is some inherent inaccuracy in this method of calculating the time a vehicle is traveling along a section of roadway or between two points.
What is needed is a method and system deployed without compromising any cellular subscriber trust and that can obtain actual accurate measurements of vehicle travel times between two discrete geographic street locations.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.